Virtualization - Sep 2023 - [PATCH vfio 11/11] vfio/virtio: Introduce a vfio driver over virtio devices

On Wed, Sep 27, 2023 at 08:20:05PM -0300, Jason Gunthorpe
wrote:
> On Wed, Sep 27, 2023 at 05:38:55PM -0400, Michael S. Tsirkin wrote:
> > On Tue, Sep 26, 2023 at 10:50:57AM -0300, Jason Gunthorpe wrote:
> > > On Tue, Sep 26, 2023 at 01:42:52AM -0400, Michael S. Tsirkin
wrote:
> > > > On Mon, Sep 25, 2023 at 09:40:59PM -0300, Jason Gunthorpe
wrote:
> > > > > On Mon, Sep 25, 2023 at 03:44:11PM -0400, Michael S.
Tsirkin wrote:
> > > > > > > VDPA is very different from this. You might
call them both mediation,
> > > > > > > sure, but then you need another word to
describe the additional
> > > > > > > changes VPDA is doing.
> > > > > > 
> > > > > > Sorry about hijacking the thread a little bit, but
could you
> > > > > > call out some of the changes that are the most
problematic
> > > > > > for you?
> > > > > 
> > > > > I don't really know these details.
> > > > 
> > > > Maybe, you then should desist from saying things like
"It entirely fails
> > > > to achieve the most important thing it needs to do!"
You are not making
> > > > any new friends with saying this about a piece of software
without
> > > > knowing the details.
> > > 
> > > I can't tell you what cloud operators are doing, but I can
say with
> > > confidence that it is not the same as VDPA. As I said, if you
want to
> > > know more details you need to ask a cloud operator.
> >
> > So it's not the changes that are problematic, it's that you
have
> > customers who are not using vdpa. The "most important thing"
that vdpa
> > fails at is simply converting your customers from vfio to vdpa.
> 
> I said the most important thing was that VFIO presents exactly the
> same virtio device to the VM as the baremetal. Do you dispute that,
> technically, VDPA does not actually achieve that?
I dispute that it is the most important. The important thing is to have
guests work.
> Then why is it so surprising that people don't want a solution that
> changes the vPCI ABI they worked hard to create in the first place?
> 
> I'm still baffled why you think everyone should use vdpa..
> 
> Jason
They shouldn't. If you want proprietary extensions then vfio is the way
to go, I don't think vdpa will support that.

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MST